When Duration seconds is defined as a non-Integer value in order to express sub-second values, instances of Fraction, ScaledDecimal, and FixedPoint were not handled correctly. If seconds is assigned as an instance of one of these classes, the printString method encounters a MessageNotUnderstood exception on #asStringUsingFormat:.
Convert instances of these classes using asFloat before creating the Duration instance.
Last updated: 9/22/14